<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>在线考试系统</title>
</head>
<body>
<h1 style="color: green">在线考试系统</h1>
用户名:<input type="text" name="username"/><br/>
密码:<input type="password" name="password"/><br/>
<button onclick="alert('登录按钮被点击！')">登录</button>
</body>
</html>